I pulled out ye olde detergent formulation handbook (yes, I have one)... I see that sodium metasilicate (powder) and sodium metasilicate pentahydrate (liquid) "provide alkalinity and can protect soft metals such as aluminum, copper, zinc, brass and tin from the corrosive effects of strongly alkaline cleaning solutions. Silicates also reduce the redeposition of soils." My book also states that STPP is often combined with sodium metasilicate to produce a synergistic effect where the two work better together. Also of note regarding STPP, it cannot solubilize fats on its own, but can with the addition of SDDBS (sodium dodecyl benzene sulfonate). Some people in this forum are under the impression that STPP can rid your machine of gunk and clean oil stains from clothing, which doesn't appear to be the case. However, my book does recommend that if you are using detergents with a precipitating softener (sodium carbonate, soda ash, wash soda, etc) in hard water, adding STPP will prevent those precipitates from agglomerating onto your washer parts. You will note that the vast majority of drum spiders in front loaders are made from aluminum, a metal that can be corroded by a strongly alkaline cleaning solution. The addition of silicates to such a solution should minimize the corrosive effects on the spider assembly.

The contractor part of me says it wouldn't be that hard to tear out the cornerbead and replace it with plastic, being I get paid for what I do, no matter what it is. Cut out the metal, stick in the plastic and mud it. But anyways... You may want to consider searching for a new contractor/handyman type, based on your recent experiences. If you have/had mold or mildew on the insulation, you may have other issues above the ceiling line. As far as 'cleaning' mold/mildew, you can really clean mold, you can only really kill with bleach or equiv. or remove the dryall. I recently had to do the same thing in my own house. I had noticed a bit of a sag in the drywall by a wall. After doing an investigation, I had discovered a condensation problem coming from my chimney that was probably going on since the house was built. I cut the drywall in that area and discovered a mold/mildew condition that was right under the ceiling joist, which I probably would not have discovered without doing my little investigation. You do not want ANY kind of mold or mildew in your house, it can cause or trigger a number of medical conditions(asthma,allergies,etc.) especially in children or the elderly. The room I was working on is for my new baby girl we have on the way. See the concern.... To answer your question of using the Bullzeye; any primer will slow the rusting process, but will not prevent it forever unless you find another way to vent the room to totally prevent any kind of condensation build-up(which, of course, is next to impossible). Being the skylight is boxed out,like they normally are, it will have the tendency to collect in that area. Even though I can't see the repaired area, I still stand by the not just spot priming thing I had said before. You will definately will see a difference. Keep in mind, this is your house, not the contractors. Unless you're okay with 'just okay', can't see it from my house in a snowstorm theories. Not to be mean, but I think you understand my point. That's why guys like me can go into a job and charge top-dollar, because I treat every job/house like my own. My company(and personal)creedo is do it once,...do it right. I hope I helped you in some way. I really hate seeing people being taken advantage of. If there is anything else I can help you with, please write and I'll respond ASAP.--Dave

Did you use the rubber gasket included and required for this connection? If so it is possible it wasn't tightened enough and many times shoddy ground threads of the heater nipple were not straight and perhaps the heat has loosened the connection.

Are you concerned about corrosion or appearance? If the humidity is high enough for corrosion to be a concern, you have other problems too. If humidity is within reasonable levels, the corrosion of the steel should not be a problem.